1. Field of Invention
This invention relates generally to catheter insertion devices, specifically to a catheter syringe conveyor with a needle guard housing.
2. History of Technology
In order to install an indwelling catheter into a blood vessel of a patient, a medical technician will often struggle with the fact that the targeted blood vessel may tend to move away from an incoming introducer needle. A second problem is that the needle is exposed for a substantial length of time during the procedure, limiting safety. A third problem arises when the targeted blood vessel is an artery; the artery is often difficult to locate. A fourth problem is that it is difficult for the technician to maintain a straight path of insertion. A fifth problem is that it is typically impossible to keep exposed fingers away from the puncture site. The present invention solves these problems.
An indwelling venous catheter is inserted into a targeted blood vessel of a patient by a qualified technician, typically for the purpose of infusing liquid substances into the patient or for occasionally removing venous blood from the patient. The catheter is inserted using a catheter syringe. After the catheter is inserted properly, the syringe is removed, and the catheter is secured to the patient.
Although the present invention is adapted for use with both venous and arterial catheters, for the purpose of clarity, this discussion will focus mostly on arterial catheters, also known as arterial lines, a-lines, or art lines. An arterial catheter is inserted into a selected artery of a patient by a technician, usually in a critical care environment within a healthcare facility. Arterial catheters are used typically for blood pressure monitoring and for patients who are in need of frequent arterial blood draws. A variety of catheters are available; a standard 20-gauge straight intravenous catheter is one type that is frequently used. The radial artery is the insertion site of choice, but other arterial sites may be used if necessary; these alternative sites include the femoral, brachial, ulnar, axillary, and dorsalis pedis arteries. Arterial blood sampling is achieved utilizing a separate access port placed onto the catheter hub of the inserted catheter, and may be performed for blood collection and for blood gas analysis. Arterial blood gas analysis is performed to determine at least the partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2), and the pH of the blood sample. These values are important in assessing pulmonary function, since these measurements indicate the status of gas exchange between the lungs and the blood.
The catheter is retained over the introducer needle of a catheter syringe. When the technician inserts the introducer needle into the artery, a flash of blood in the blood receptacle of the syringe signals the technician that proper placement of the needle within the artery has occurred. The catheter is then slid off of the introducer needle by hand, deeper into the artery, and the needle is removed from within the catheter, leaving only the catheter in the artery. The catheter hub is then connected to a transducer tubing system, and then the catheter hub is secured to the patient's wrist.
A variation of the standard arterial catheter syringe is a syringe with a guide wire unit attached. The guide wire is used to help guide the catheter into the artery; after the technician has inserted the introducer needle properly into the artery, the technician advances the guide wire through the hollow needle and into the artery, providing a feed over which the catheter can be fed into the artery.
A modified Allen Test (collateral circulation test) should always be performed by the technician before inserting a needle and catheter into a patient's radial artery. The Allen Test determines if blood is capable of flowing through the ulnar artery. The ulnar artery is the only other source of blood to the hand aside from the radial artery. A negative test result is indicative of inadequate collateral blood supply to the hand and requires the selection of another location as the site for catheter insertion.
The catheter insertion procedure is difficult and prone to errors, even when the technician has ample experience. Because of the traumatic nature of the procedure, and the large number of complications that may arise from complications, it is important for the technician to try to insert the catheter properly on the first attempt. Prior art has seriously failed to provide technicians with adequate means to insert an arterial catheter regularly on the first attempt.
An unrestrained blood vessel may tend to move away from an incoming needle, particularly in older patients whose skin has become loose and has lost elasticity. A loss of elasticity in the skin creates a loss of stability around the blood vessel, which allows the vessel to roll around under the surface of the skin. It is possible for a needle to push the vessel away from its path, causing the technician to miss the targeted vessel completely. The present invention solves this problem by providing a blood vessel stabilizer to hold the vessel in place during a catheter insertion attempt.
Currently, the technician will press her or his finger over an anticipated arterial puncture site and then estimate where the artery lies under that finger; it is a rough estimate and the technician often miscalculates. Alternatively, the technician may place two fingers over the artery and attempt to hold the artery in place between the fingertips, inserting the needle between the two fingertips to attempt to penetrate the artery. This method has its limitations; the technician should have a tight pair of gloves, cannot have long finger nails, and will rely on bulky finger tips to pinpoint a relatively thin artery between them, and this technique is impossible to use on infants and small children. One embodiment of the present invention uses a blood vessel stabilizer to hold the artery within two integrated stabilizer fingers at the base of the device, and it partially occludes the artery during use; this creates a stable and augmented pulse at the site where the needle will enter the artery, thus simplifying palpation of the artery and vastly diminishing the labor involved in identifying where to insert the needle. A blood vessel stabilizer further allows the technician to keep any exposed extremities away from the puncture site while inserting the needle into the site, thus improving safety.
Because of low blood pressure, a patient's pulse may be weak and hard to locate. It is sometimes necessary for the technician to perform an arterial puncture “blindly,” merely stabbing the site where the technician considers the best option for obtaining arterial access. The present invention helps to create an augmented pulse that is palpable even in cases of low blood pressure.
Most protocols allow a technician to try three consecutive needle insertions without removing the needle tip beyond the subcutaneous tissue. As the angle of insertion changes within the dermis, the needle slices through the tissue in its path, and may even lacerate the artery. Any change in the angle of needle insertion can inflict severe pain onto a conscious patient.
Because of the structural design of the present invention, a straight, unswerving path of needle insertion into the blood vessel is assured. Currently, the often unsteady hand of the technician is used to guide the needle down into the blood vessel. A nervous hand can become quite jittery, and even a calm hand does not guarantee a straight path of insertion into and out of the vessel. The present invention provides a considerable improvement in this regard; pressing the stabilizer, at the base of the invention, down near the insertion site provides stability to the hand of the technician. The straight slot within the housing, which supports the syringe, vastly improves the likelihood of a direct and controlled line of insertion and extraction of the needle during a catheter insertion procedure, minimizing pain and trauma within the patient's dermal tissues and artery.
Often, the unrestrained nature of the current methods for inserting a catheter into a blood vessel causes the introducer needle to become accidentally extracted from within the blood vessel during a catheter insertion attempt. The present invention prevents this common mishap, by providing a solid, steady housing within which the syringe is securely held in place during the procedure.
According to standard procedure protocols, a catheter introducer needle should enter an artery at a steady angle of 30 to 45 degrees in relation to the artery; prior art relies on the technician to maintain that angle without any support. A proper angle of needle insertion is assured using one embodiment of the present invention, as a result of the base of the stabilizer fingers being angled in relation to the housing slot within which the syringe is maneuvered.